Structural adhesives

Abstract

An adhesive formulation having an adduct of an epoxy resin and an elastomer, a phenoxy epoxy hybrid resin supplied as a solution formed by dissolving a phenoxy resin in a liquid epoxy resin to form a pre-formed dissolution product, a core/shell polymer, and one or more additional epoxy resins. The adhesive formulation may include a curing agent, blowing agent, filler, accelerator, or a combination.

The invention claimed is: 
     
       1. An adhesive formulation comprising:
 i) an adduct of an epoxy resin and an elastomer, wherein the adhesive formulation contains from about 7% to about 20% by weight of the adduct based on the adhesive formulation; 
 ii) a phenoxy epoxy hybrid resin supplied as a solution formed by dissolving a phenoxy resin in a liquid epoxy resin to form a pre-formed dissolution product; 
 iii) a core/shell polymer, wherein the adhesive formulation contains from 5% to 30% by weight of the core/shell polymer; and 
 iv) one or more additional epoxy resins; and 
 wherein the adhesive formulation includes between about 55% by weight and about 70% by weight total epoxy resin, wherein the total epoxy resin is the liquid epoxy resin of the phenoxy epoxy hybrid resin and the one or more additional epoxy resins; and 
 wherein the adhesive formulation contains between 3% and 10% by weight of the phenoxy resin. 
 
     
     
       2. The adhesive formulation according to  claim 1 , wherein the adhesive formulation contains from about 7% to about 15% by weight of the adduct based on the adhesive formulation. 
     
     
       3. The adhesive formulation according to  claim 1 , wherein the adduct includes about 1:5 to about 5:1 parts of epoxy to elastomer. 
     
     
       4. The adhesive formulation according to  claim 1 , wherein the elastomer in the adduct is selected from natural rubber, styrene-butadiene rubber, polyisoprene, polyisobutylene, polybutadiene, isoprene-butadiene copolymer, neoprene, nitrile rubber, butyl rubber, polysulfide elastomer, acrylic elastomer, acrylonitrile elastomers, silicone rubber, polysiloxanes, polyester rubber, diisocyanate-linked condensation elastomer, EPDM (ethylene-propylene diene rubbers), chlorosulphonated polyethylene, fluorinated hydrocarbons, and any combination thereof. 
     
     
       5. The adhesive formulation according to  claim 1 , wherein the adduct of the epoxy resin and the elastomer is derived from a butadiene acrylonitrile rubber. 
     
     
       6. The adhesive formulation according  claim 1 , wherein the phenoxy resin is of the formula 
       
         
           
           
               
               
           
         
         where n is from 30 to 100. 
       
     
     
       7. The adhesive formulation according to  claim 1 , wherein the core/shell polymer has a ductile core and a rigid shell which is compatible with the other components of the adhesive formulation. 
     
     
       8. The adhesive formulation according to  claim 1 , wherein the core/shell polymer includes a first polymeric material and a second polymeric material, wherein the first polymeric material and the second polymeric material include elastomers, polymers, thermoplastics, copolymers, and combinations thereof. 
     
     
       9. The adhesive formulation according to  claim 8 , wherein the first polymeric material and second polymeric material are selected from styrenics, acrylonitriles, acrylates, acetates, polyamides, polyethylenes, and any combination thereof. 
     
     
       10. The adhesive formulation according to  claim 1 , wherein the core/shell polymer is a graft copolymer in which styrene, acrylonitrile, or methyl methacrylate, are grafted onto a core made from polymers of soft or elastomeric compounds. 
     
     
       11. The adhesive formulation according to  claim 10 , wherein the core includes other copolymerizable containing compounds, selected from styrene, vinyl acetate, methyl methacrylate, butadiene, and isoprene. 
     
     
       12. The adhesive formulation according to  claim 10 , wherein the core includes a cross linking monomer having two or more nonconjugated double bonds. 
     
     
       13. The adhesive formulation according to  claim 10 , wherein a shell portion of the core/shell polymer is polymerized from alkyl acrylates and/or methacrylates. 
     
     
       14. The adhesive formulation according to  claim 1 , comprising from about 0.001% to about 10% by weight of a curing agent. 
     
     
       15. The adhesive formulation according to  claim 14 , wherein the curing agent is selected from aliphatic or aromatic amines or their respective adducts, amidoamines, polyamides, cycloaliphatic amines, anhydrides, polycarboxylic polyesters, isocyanates, phenol-based resins, and mixtures thereof. 
     
     
       16. The adhesive formulation according to  claim 14 , wherein the adhesive formulation comprises an accelerator for the curing agent. 
     
     
       17. The adhesive formulation according to  claim 1 , wherein the adhesive formulation contains between 7% and 15% by weight of the liquid epoxy resin of the phenoxy epoxy hybrid resin. 
     
     
       18. The adhesive formulation according to  claim 1 , wherein the adhesive formulation comprises a blowing agent. 
     
     
       19. The adhesive formulation according to  claim 1 , wherein the adhesive formulation comprises a filler. 
     
     
       20. The adhesive formulation according to  claim 1 , wherein the adhesive formulation comprises one or more liquid polysulfides.